The invention is an intracorporeal device and method for grasping objects within a patient""s body and withdrawing the grasped objects from the patient""s body. More specifically, the intracorporeal device is a grasping device and system for removing an object such as thrombus from a patient""s vasculature, particularly the cerebral vascular anatomy, where such an object may cause a debilitating stroke.
Several devices and methods have been previously disclosed for removing objects from different regions of the body. Some previous devices and methods, hereafter referred to as xe2x80x9cgraspingxe2x80x9d devices, are intended for grasping or engaging an object where it resides in the body and removing it from that location. These grasping devices are designed to be delivered to the particular site where the target object resides in the bodyxe2x80x94the object is then engaged by the grasping device and removed from the body. More specific examples of grasping devices have been disclosed for specifically engaging and removing the following from respective body cavities or other locations: gall stones, foreign objects such as implanted medical devices e.g. xe2x80x9csnaresxe2x80x9d, and vascular occlusions such as occlusive thrombi. In one particular device that is disclosed for engaging and removing a calculus principally kidney stones, a grasping assembly includes a plurality of arms arranged in a circumferential pattern in order to capture a target stone to capture the target calculus between them. The device operates via a centrally located plunger that is adjustable longitudinally along proximal tapers of the arms in order to force their detached distal ends apart to open the array for placement around the kidney stone calculus.
Other previously disclosed devices and methods are designed to provide a filter for catching or trapping emboli flowing through a body lumen, such as a blood filter for providing a cage across a blood vessel that is designed to catch debris flowing along the blood vessel downstream from an intervention or other embolic event. Some such filtering devices and methods are intended for removing the caught calculi after it is trapped in the filter. For example, one such known device is a probe-like strainer device that is placed retrograde through a puncture wound in a femoral artery downstream from a peripheral angioplasty site in order to catch emboli flowing downstream from an angioplasty or atherectomy site as a filter. This device includes a plurality of tines that open within the femoral artery in cone shaped arrangement that is constructed specifically for catching emboli flowing into the filter, such as by either providing a sufficiently large number of tines or by providing lateral members extending between adjacent tines to form a web-like strainer structure.
More specific examples of filtering and grasping devices and associated methods targeting specific calculi and the like for removal from various region of the body are disclosed in the following U.S. Patent references:
U.S. Pat. No. 4,612,931 to Dormia; U.S. Pat. No. 4,625,726 to Duthoy; U.S. Pat. No. 4,873,978 to Ginsburg; U.S. Pat. No. 5,064,428 to Cope et al.; U.S. Pat. No. 5,300,086 to Gory et al.; U.S. Pat. No. 5,330,482 to Gibbs et at.; U.S. Pat. No. 5,387,219 to Rappe; U.S. Pat. No. 5,846,248 to Chu et al.; U.S. Pat. No. 5,895,398 to Wensel et al.; U.S. Pat. No. 5,908,435 to Samuels; U.S. Pat. No. 5,944,728 to Bates; U.S. Pat. No. 5,968,057 to Taheri; U.S. Pat. No. 5,972,019 to Engelson et al.; U.S. Pat. No. 6,013,086 to Ouchi et al.; and U.S. Pat. No. 6,027,520 to Tsugita et al.
Recent developments in medical technology and associated treatments have been focused on clearing or removing thromboembolisms or xe2x80x9cblood clotsxe2x80x9d from the cervical and cerebral vasculature in order to treat thromboembolic stroke victims. Thromboembolic stroke is a life threatening condition that consists of arrested blood flow to a region of the brain due to a thromboembolisum blocking a blood vessel feeding that region. Such thrombi often originate in the left heart chambers, break free into the aorta and flow downstream into the cervical neck arteries e.g. carotid arteries, and then ultimately lodge into a narrowed vessel somewhere down the narrowing vascular tree of the cerebral arteries associated with the brain in the head. Once lodged, the thrombus occludes flow along the vessel downstream of the blockage, thus arresting blood flow to the downstream blood vessel and causing the stroke.
Several recent techniques have been disclosed for ablating or xe2x80x9cbreaking upxe2x80x9d a thromboembolism at a cervical or cerebral occlusion location in order to treat stroke. According to one known technique, a standard guidewire, more commonly used to guide medical catheter devices to remote body spaces like a rail, is used to xe2x80x9cDotterxe2x80x9d through and break up the occluding clot in order to clear it from the occlusive site. However, fragments of the clot then break free to flow to a downstream site, often still resulting in harmful stroke to other regions of brain tissue. Other more recently disclosed devices and methods are intended to ablate the clot with focused energy delivery, such as for example sonic or laser ablation. However, these techniques also carry the risk of stroking downstream brain tissue. In addition, several of these approaches are very expensive and require specialized hardware to operate the respective ablation catheters.
Several grasping device assemblies and methods have been disclosed specifically for removing thrombi from the cervical and cerebral vessels in order to treat thromboembolic stroke. However, many of these devices have grasping assemblies that are not well adopted for delivery to distal regions of the cerebral vessels where many thromboembolisms are known to cause a debilitating stroke. For example, such known devices are not well designed for delivery to distal cerebral vascular locations through standard cerebral vascular delivery catheters that typically have delivery lumens with very small inner diameters, such as for example through delivery catheters with inner diameters of about 0.042 inch or less, generally adapted to track over a guidewire with an outer diameter of about 0.032 inch or 0.035 inch, or through still smaller delivery catheters with inner diameters of about 0.022 inch, generally adapted to track over a 0.018 inch or less OD guidewire, or through the still smaller standard delivery catheters having inner diameters of about 0.018 inch or less, generally adapted to track over a 0.014 inch OD guidewire. In addition, many of these assemblies and associated methods may not be predictable or easy to operate when engaging and removing an offending blood clot from a cerebral vessel, and particularly from distal cerebral vessels.
Distal cerebral blood vessels typically have inner lumens less than 4 mm and are quite tortuous. For example they have a plurality of 180xc2x0 bends with a radius of curvature not greater than about 2 cm with spacing between the bends being not greater than about 10 cm. Advancing instruments for therapeutic or diagnostic uses through such anatomy is difficult.
There is a present unmet need for devices for capturing and removing thromboembolisms and other objects from small tortuous body lumens such as distal cerebral vessels.
This invention is directed to an intracorporeal grasping device and system for capturing an object or mass such as a thromboembolic occlusion in a patient""s vasculature and the method of such capturing and removal.
The grasping device has an elongated core member with proximal and distal core sections and a grasping assembly secured to the distal end of the elongated core member which has a plurality of arms circumferentially and preferably uniformly disposed about the longitudinal axis of the grasping device. The proximal ends of the arms are secured to the distal end of the elongated core member. The grasping assembly has contracted and expanded configurations. In the expanded configuration within a body lumen, the arms have distal sections which are spaced from and essentially parallel to the longitudinal axis of the elongated core member (e.g. xc2x15xc2x0 from the longitudinal axis).
In one presently preferred embodiment of the invention, the grasping system includes a delivery catheter for delivery of the grasping device to the desired location within the patient""s vasculature. The delivery catheter has proximal and distal core member sections, ports in the proximal and distal ends and an inner lumen extending within the delivery catheter to and in fluid communication with the ports. The inner lumen is configured to slidably receive the grasping device with the grasping assembly thereon in the contracted configuration. When the grasping assembly extends out the port in the distal end of the delivery catheter, it deploys to its expanded configuration with the distal portion of the arms spaced from and parallel to the longitudinal axis of the grasping device. The delivery catheter is shorter than the grasping device so that the proximal end of the grasping device extends out the proximal port of the delivery catheter when the grasping assembly on the device extends out the port in the distal end of the delivery catheter.
In the grasping procedure, the delivery catheter is advanced to a location within the patient""s vasculature, or other body lumen, that is proximally adjacent to the object or mass to be grasped such as a thrombus or embolism. The grasping device is advanced within the delivery catheter until the assembly of the grasping device extends out the port in the distal end of the delivery catheter and deploys in the expanded configuration. The grasping device is further advanced so the distal arm sections extend around the periphery of the object or mass to be grasped. Once arms are properly positioned about the object or mass, the delivery catheter is distally advanced while the grasping device is held in place so that the distal end of the delivery catheter presses against the proximal arm sections of the grasping assembly forcing the arms of the assembly into the contracted or partially contracted configuration. The retaining or grasping elements on the distal ends of the distal arm sections are forced into the object or mass when the assembly is forced into the contracted configuration and thereby facilitates the grasping and subsequent removal of the object or mass.
The grasping system is predictable and easy to use in capturing and removing a thromboembolic occlusion, particularly from a cerebral vessel. Moreover, it is simple and inexpensive to make and use for the treatment of cerebral thromboembolic stroke.
One presently preferred embodiment of the invention includes a guide catheter in addition to the delivery catheter and a grasping device. The guide catheter has a guiding passageway extending between ports in the proximal and distal ends of the catheter and is adapted to be positioned within a vascular anatomy of the patient such that the distal port is located at a desired location such as at a cervical vessel and the proximal end portion of the guide catheter extends from a vascular access site, such as a femoral artery, with the proximal port located externally of the patient. The guide catheter is shorter than the delivery catheter and the inner lumen of the guide catheter is configured so that the delivery catheter can be slidably disposed within the guiding catheter inner lumen with the delivery catheter""s distal end portion extended distally through the guide catheter""s distal port with the delivery catheter distal port positioned at the cerebral vessel, and further such that the delivery catheter proximal port is located proximally of the guide catheter proximal port externally of the patient. In this manner the grasping device may be advanced through the inner lumen of the delivery catheter by the manipulation of the proximal end of the elongated core member which extends out of the proximal port of the delivery catheter. This also facilitates holding the proximal end of the grasping device and the distal advance of the delivery catheter when forcing the grasping assembly on the distal end of the elongated core member of the grasping device into a contracted configuration when capturing and withdrawing an object.
The grasping device and system of the invention are particularly suitable for grasping and removal of a cerebral thrombus and can be delivered to the desired location of a thromboembolism through neurovascular delivery catheters having an inner lumen with a diameter that is 0.042 inch (1.067 mm) or less, or even 0.022 inch or 0.018 inch (0.559 or 0.457 mm) or less, respectively.
Therefore, the invention is a medical device system and method for removing a thrombus from a location within a cerebral vessel associated with a brain of a patient, and includes the following embodiments, aspects, and further beneficial variations.
According to one further aspect of the invention, the system may include a guide member such as a conventional guidewire with a proximal end portion and a distal end portion that is adapted to be positioned at the location of the object to be removed. The guide member is adapted to be slidably disposed within the inner lumen of the delivery catheter so that the delivery catheter can track over the guide member in order to position the distal port of the delivery catheter immediately adjacent to the location of the object to be captured.
The system of the invention may also include an introducer with a proximal end portion with a proximal introducer bore associated with a hemostatic valve, a distal end portion with a distal introducer port, and an introducer passageway extending between the proximal and distal introducer ports. The distal end portion of the introducer is adapted to be positioned across the vascular access site with the distal introducer port within the patient""s vasculature and with the proximal introducer port and hemostatic valve positioned externally of the patient. The guide catheter is adapted to be introduced into the vascular access site through the introducer passageway for positioning of the guide catheter distal end portion along the desired body lumen.
For cerebral use, the grasping device is about 135 to 175 cm long preferably at least 150 cm long.
The guide catheter and the, delivery catheter, are configured with respective lengths that are specially adapted for delivery of the grasping assembly to a distal region of a patient""s vascular anatomy. In one regard, the guide catheter may be between about 90 and about 110 cm long, the delivery catheter may be between about 125 cm and about 160 cm long.
Each of the arms of the grasping assembly is adjustable with an applied force from the expanded configuration to a partially or completely contracted configuration, respectively. In one further beneficial variation, each arm is adjustable with force from the expanded configuration to the partially contracted and contracted configurations respectively, by pressing the distal end portion of the delivery catheter against the inclined proximal portion of the arms. Preferably the arms have an outwardly inclined proximal sections extending distally away from the distal end of the core wire at an angle with respect to the longitudinal axis. The inclination of the proximal sections allow for controllable adjustment of the positioning for the arm""s distal end portion by advancing the outer delivery catheter along the inclined proximal sections.
The distal end portion of the arms terminate with an engaging element such as a tooth that is oriented radially inwardly toward the longitudinal axis. By adjusting the grasping assembly with the arms around the object from the expanded configuration to the contracted configuration, each grasping element is forced into the object to be removed.
The grasping assembly""s arms may be arranged in a manner that maximizes the ability to grasp and remove the target object, but while minimizing the cross-section and overall size of the arm assembly within the delivery catheter and within the body lumen. More specifically, when the grasping assembly is in the expanded configuration at the location of the object to be grasped, the arms are arranged in such a manner that an embolism with an outer diameter that is equal to or less than ⅓ the inner diameter of the body lumen at the location may pass through the grasping assembly. In a further variation generally associated with larger arms or more arms, the plurality of arms in the expanded configuration is adopted to allow an object with an outer diameter that is equal to or less than xc2xc the inner diameter of the body lumen at the location to pass through the grasping assembly.
The grasping assembly should have at least 3 arms arranged in a circumferential pattern about the longitudinal axis of the grasping device. Usually no more than 6 arms are needed. A presently preferred embodiment of the grasping device has four arms, which are uniformly spaced, e.g. at intervals of approximately 90xc2x0 about the longitudinal axis of the device.
The elongated core member of the grasping device is preferably constructed at least in part of a metallic core wire. In one highly beneficial variation, a coil surrounds and is secured to the distal end of the metallic core wire. Preferably the coil is made from a metal and is sufficiently radiopaque to facilitate fluoroscopic observation. The elongated core member of the grasping device has enough stiffness to advance the arms of the grasping assembly in the expanded condition around the object to be grasped and the distal end portion of the elongated core member and the grasping assembly in the first condition are sized and flexible enough to be advanced through vascular anatomy not greater than about 4 mm in diameter and having at least two 180 degree bends with a radius of curvature not greater than about 2 cm and a spacing between bends not greater than about 10 cm. These dimensions are typical for cerebral arteries.
Each of the arms may be secured to the elongated core member of the grasping device at a location distally of the coil. The elongated core member of the grasping device should include a lubricious coating such as a fluoropolymer, e.g. Teflon(copyright) or suitable hydrophilic coating. The proximal core portion of the core wire has a uniform outer diameter and the distal core portion is more flexible than the proximal core section. The increased flexibility can be obtained by smaller transverse dimensions or the use of a more flexible material for the distal core section. The distal core portion is preferably tapered in the distal direction to smaller transverse dimensions. In another variation, the outer diameter of the proximal portion of the core wire is equal to or less than about 0.035 inch and the distal portion of the core wire has an outer diameter equal to or less than about 0.018 inch.
The distal core portion of the elongated core member is preferably at least 25% more flexible than the proximal core portion. The core member may have a shaped or shapeable distal end.
The system of the invention includes positioning a guide catheter, delivery catheter, and grasping device in particular locations within the anatomy of the patient in order to grasp the object from the location. More specifically, this method of use may includes positioning the guide catheter such that a distal guide port of the guide catheter is positioned at a location within the patient""s vasculature and the proximal end portion of the guide catheter extends across a vascular access site with a proximal guide port of the inner lumen of the guide catheter positioned externally of the patient. The delivery catheter is positioned within the inner lumen of the guide catheter with a distal end portion of the delivery catheter extending distally through the distal guide port of the guide catheter with the distal delivery port of the delivery catheter at or proximal to the location within the patient""s vasculature. The proximal end portion of the delivery catheter extends proximally through the proximal port of the guide catheter with a proximal delivery port of the inner lumen of the delivery catheter located externally of the inner lumen of the guide catheter and of the patient.
After grasping the object from the location, the delivery catheter and grasping device may be removed from the patient. The guide catheter may be removed from the patient while the grasping assembly and grasped object are located within the inner lumen of the guide catheter. An alternative variation includes removing the grasping assembly and engaged object from the patient proximally through the proximal guide port while the distal guide port is located within the body lumen.
The present invention provides a predictable and easy to use device and system for grasping an object such as a thromboembolic occlusion from a patients body lumen particularly from a cerebral blood vessel. These and other advantages of the invention become apparent from the following detailed description and the accompanying exemplary drawings.